Manufacturers of consumer metal products and machine parts will often contract with a foundry in order to produce metal castings for their production purposes. Foundries are usually large factories where raw metals are heated in high powered furnaces until they become liquid. Once the metal is in liquid form, it is then poured into a pre-shaped mold where it is allowed to harden. Once the metal has cooled, it will then be removed, taking the shape of the mold. Foundries will often specialize in the casting one type of metal, such as iron, steel, bronze, brass, or aluminum, and will often be able to use custom molds to meet their clients specific needs.